1. Field of the Invention
This invention relates to means for enabling stopped-down measurement in a single lens reflex camera provided with a full-aperture measuring system when an interchangeable lens having a manually controlled diaphragm or an interchangeable lens having a preset diaphragm ring with a lens mount of different type from that of the camera is mounted to the camera.
2. Description of the Prior Art
In a single lens reflex camera provided with an automatic exposure control means of TTL type (wherein light passing through the taking lens is measured) which is capable of performing full-aperture measurement, a diaphragm interlocking member which is engaged with a preset diaphragm ring of the interchangeable lens is provided. The diaphragm interlocking member is connected with a variable resistor in an automatic exposure control circuit so that the resistance of the variable resistor may be changed in accordance with the position of the preset diaphragm ring indicative of the diaphragm value to which the diaphragm is to be stopped down in response to the shutter release operation. Thus, the measurement of the scene brightness can be performed with reference to the diaphragm value which will actually effect in the photographying operation even without actually stopping down the diaphragm to such a value. Namely, a full-aperture measurement can be conducted by use of the above system employing the diaphragm interlocking member.
In the above described type of single lens reflex cameras, it is impossible to make a stopped-down measurement when an interchangeable lens having a manually operable diaphragm control ring or an interchangeable lens having a lens mount of different type from that of the camera body is mounted to the camera. In case where a lens having a different type of lens mount from that of the camera body is desired to be mounted to the camera, a connecting attachment is interposed between the lens and the camera body. When the connecting attachment is interposed between the lens and the camera body, the diaphragm interlocking member cannot be connected with the preset diaphragm ring and accordingly it becomes impossible to conduct a full-aperture or stopped-down measurement.